From 0583afb6ea5b30b82da08168cd7e8d3bc1cfebbd Mon Sep 17 00:00:00 2001
From: Yann Ylavic <ylavic@apache.org>
Date: Tue, 10 Oct 2017 10:54:48 +0000
Subject: [PATCH] ab: Make the TLS layer aware that the underlying socket is
 nonblocking, and use/handle POLLOUT where needed to avoid busy IOs and
 recover write errors when appropriate.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1811664 13f79535-47bb-0310-9956-ffa450edef68
---
 CHANGES      |  4 ++++
 support/ab.c | 67 ++++++++++++++++++++++++++++++++++++++--------------
 2 files changed, 53 insertions(+), 18 deletions(-)

diff --git a/CHANGES b/CHANGES
index e9d54adc6e..4a81e947aa 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,10 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache 2.5.0
 
+  *) ab: Make the TLS layer aware that the underlying socket is nonblocking,
+     and use/handle POLLOUT where needed to avoid busy IOs and recover write
+     errors when appropriate.  [Yann Ylavic]
+
   *) ab: Keep reading nonblocking to exhaust TCP or SSL buffers when previous
      read was incomplete (the SSL case can cause the next poll() to timeout
      since data are buffered already).  PR 61301 [Luca Toscano, Yann Ylavic]
diff --git a/support/ab.c b/support/ab.c
index d8486ea769..89310a0df8 100644
--- a/support/ab.c
+++ b/support/ab.c
@@ -776,8 +776,8 @@ static void ssl_proceed_handshake(struct connection *c)
             do_next = 0;
             break;
         case SSL_ERROR_WANT_WRITE:
-            /* Try again */
-            do_next = 1;
+            set_polled_events(c, APR_POLLOUT);
+            do_next = 0;
             break;
         case SSL_ERROR_WANT_CONNECT:
         case SSL_ERROR_SSL:
@@ -827,26 +827,42 @@ static void write_request(struct connection * c)
 
 #ifdef USE_SSL
         if (c->ssl) {
-            apr_size_t e_ssl;
-            e_ssl = SSL_write(c->ssl,request + c->rwrote, l);
-            if (e_ssl != l) {
-                BIO_printf(bio_err, "SSL write failed - closing connection\n");
-                ERR_print_errors(bio_err);
-                close_connection (c);
+            e = SSL_write(c->ssl, request + c->rwrote, l);
+            if (e <= 0) {
+                switch (SSL_get_error(c->ssl, e)) {
+                case SSL_ERROR_WANT_READ:
+                    set_polled_events(c, APR_POLLIN);
+                    break;
+                case SSL_ERROR_WANT_WRITE:
+                    set_polled_events(c, APR_POLLOUT);
+                    break;
+                default:
+                    BIO_printf(bio_err, "SSL write failed - closing connection\n");
+                    ERR_print_errors(bio_err);
+                    close_connection (c);
+                    break;
+                }
                 return;
             }
-            l = e_ssl;
+            l = e;
             e = APR_SUCCESS;
         }
         else
 #endif
+        {
             e = apr_socket_send(c->aprsock, request + c->rwrote, &l);
-
-        if (e != APR_SUCCESS && !APR_STATUS_IS_EAGAIN(e)) {
-            epipe++;
-            printf("Send request failed!\n");
-            close_connection(c);
-            return;
+            if (e != APR_SUCCESS) {
+                if (!APR_STATUS_IS_EAGAIN(e)) {
+                    epipe++;
+                    printf("Send request failed!\n");
+                    close_connection(c);
+                    return;
+                }
+                if (!l) {
+                    set_polled_events(c, APR_POLLOUT);
+                    return;
+                }
+            }
         }
         totalposted += l;
         c->rwrote += l;
@@ -1387,6 +1403,7 @@ static void start_connect(struct connection * c)
         ssl_rand_seed();
         apr_os_sock_get(&fd, c->aprsock);
         bio = BIO_new_socket(fd, BIO_NOCLOSE);
+        BIO_set_nbio(bio, 1);
         SSL_set_bio(c->ssl, bio, bio);
         SSL_set_connect_state(c->ssl);
         if (verbosity >= 4) {
@@ -1535,8 +1552,13 @@ read_more:
                      && good == 0) {
                 return;
             }
-            else if (scode != SSL_ERROR_WANT_WRITE
-                     && scode != SSL_ERROR_WANT_READ) {
+            else if (scode == SSL_ERROR_WANT_READ) {
+                set_polled_events(c, APR_POLLIN);
+            }
+            else if (scode == SSL_ERROR_WANT_WRITE) {
+                set_polled_events(c, APR_POLLOUT);
+            }
+            else {
                 /* some fatal error: */
                 c->read = 0;
                 BIO_printf(bio_err, "SSL read failed (%d) - closing connection\n", scode);
@@ -1750,6 +1772,7 @@ read_more:
         c->read = c->bread = 0;
         /* zero connect time with keep-alive */
         c->start = c->connect = lasttime = apr_time_now();
+        set_conn_state(c, STATE_CONNECTED);
         write_request(c);
     }
 }
@@ -1996,6 +2019,7 @@ static void test(void)
             }
             if (rtnev & APR_POLLOUT) {
                 if (c->state == STATE_CONNECTING) {
+                    /* call connect() again to detect errors */
                     rv = apr_socket_connect(c->aprsock, destsa);
                     if (rv != APR_SUCCESS) {
                         set_conn_state(c, STATE_UNCONNECTED);
@@ -2020,7 +2044,14 @@ static void test(void)
                     }
                 }
                 else {
-                    write_request(c);
+                    /* POLLOUT is one shot */
+                    set_polled_events(c, APR_POLLIN);
+                    if (c->state == STATE_READ) {
+                        read_connection(c);
+                    }
+                    else {
+                        write_request(c);
+                    }
                 }
             }
         }
-- 
2.50.1